Field studies on the association between amyloid arthropathy and Mycoplasma synoviae infection, and experimental reproduction of the condition in brown layers

Approximately 20% of outbreaks of amyloid arthropathy in The Netherlands we re earlier attributed to Enterococcus faecalis but there was no explanation for the remaining cases. In a further study, material from the joints of 1 0 birds from each of 10 affected brown layer flocks and two broiler flocks was cultured in several bacteriological media. E. faecalis was isolated fro m one layer flock but Mycoplasma synoviae was recovered from purulent joint s in six of the layer flocks and both broiler flocks. Brown layers were the n infected experimentally with one of the M. synoviae isolates to assess it s arthropathic and amyloidogenic potential. Using Congo red staining, artic ular amyloid deposits were seen 12 weeks after intra-articular or intraveno us inoculation in almost all birds. After intra-articular inoculation of th e left knee joint the contralateral hock tendon sheath tended to be affecte d, while hock and foot joints were mainly affected after intravenous inocul ation. Amyloid deposits were seen in livers and spleens of many birds. This is the first demonstration of arthropathic strains of M. synoviae with an association with amyloid arthropathy, while for one isolate its amyloidogen ic potential was shown experimentally.